1. Field of Invention
This invention relates to computers and computer software. More specifically, this invention relates to displaying information in a window on a computer display, when a window displays only part of its related information.
2. Description of Prior Art
When a computer user views an image in a window, the image can be a text, a picture, a movie, a content of a computer folder, etc., the window often displays only a portion of its related information. To view other portions a user needs to scroll the window. In current Graphical User Interfaces (GUIs) scrolling is typically carried out with a scroll bar. There are also other techniques, such as dragging, zooming, using a navigation map, and the like. In the present description all these techniques are referred to as scrolling. Therefore, scrolling is understood here in a broad sense, in the spirit of the U.S. Patent Classification System, which, for instance, gives the following description of subclass 784 of class 345: “Window scrolling: This subclass is indented under subclass 781. Subject matter wherein, when a window displays only part of its related information, the user can selectively control which portion is displayed.” (Class 345, Computer graphics processing, operator interface processing, and selective visual display systems. Class definition. Downloaded from the official website of the USPTO on Jan. 1, 2002). In the context of the present invention scrolling is understood as any method or technique used to make a window display a different portion of its related information. Besides, scrolling in the context of the present invention includes not only scrolling controlled by a user, but also autoscrolling, scrolling of items on a menu, resizing of a window, and the like.
Even though the basic principles of the current invention apply to all types of scrolling, in the description below these basic principles are illustrated with scrolling windows most typical of current GUI environments, such as operating systems for personal digital assistants (PDAs) or personal computers (PCs). Windows typical of current operating systems for PCs, such as Mac OS or Microsoft Windows, feature scroll bars, so that a user can scroll through a content by a large increment, substantially the whole “page”, or by a small increment, for example one line of text or one row of icons at a time. FIG. 1 depicts a window 10, which is a part of a GUI provided by an operating system, such as Windows 2000, or by a browser that accesses and displays information from the Internet; or by a word processing program; or by other software through which a user can view information. A content 12 depicted in FIG. 1 is a document consisting of lines of text, schematically represented in FIG. 1 as digits and broken lines. The window 10 could contain not only texts but also graphical representations of objects or other information. The window 10 further includes a scroll bar 13.
The content 12 may contain more information than can be displayed in the window 10 at the same time. FIG. 1A depicts a portion 11 of the content 12 that is displayed in the window 10. The scroll bar 13 allows a user to scroll through portions of the content 12, which are not immediately displayed in the window 10. The scroll bar 13 includes a scroll shaft 14, a scroll box 15, and scroll arrows 16 and 17. By clicking on the scroll arrows 16 or 17, the user can scroll up or down by a small increment, such as one line of text. By clicking on the scroll shaft 14 above or below the scroll box 15 a user can scroll the content by a large increment, substantially the whole page displayed in the window 10. FIG. 1B depicts the window 10 after it has been scrolled down by a large increment. Although not depicted, the window 10 may also include a horizontal scroll bar.
FIG. 2 depicts a screen 20 that may be provided on a handheld computer device, such as a PDA. The screen displays records 21, schematically depicted as broken lines. The screen displays only a portion of all records on a list. To see another portion of the records a user has to scroll through the list, for example by touching a triangle-shaped control 22 on the screen. Windows of the type depicted in FIG. 2 are typical of small screen devices, such as PDAs, mobile phones, other wireless devices, computer games, control components of various equipment, etc. These windows in most cases are substantially of the same size as the screen itself, and often it is possible to provide only one window on a display.
Scrolling windows of the types shown in FIG. 1 and FIG. 2, as well as other possible types, are within the scope of the present invention.
The present invention addresses a common problem associated with scrolling windows: users often “loose their place” on the page after scrolling. When a window is scrolled, new page usually does not start with new information, that is, information not displayed before scrolling. There is typically an overlapping between the currently displayed portion and the previous portion. For example, as shown in FIG. 1B, scrolling through a text by a large increment, by clicking on the scroll shaft 14 or by pressing a PageDn key on a keyboard (not depicted in FIG. 1), may result in displaying a new portion 18 of the content 12 in the window 10; the portion 18 begins with two lines of text that overlap from the portion 12.
There may be good reasons for such an overlapping. In particular, it might help the user relate new text fragments displayed after scrolling to what the user had read before scrolling and thus support the continuity of attention and understanding.
However, possible advantages of such an overlapping come at a price: locating new information on a page becomes a more complex cognitive task. When a portion of content displayed after scrolling contains information also displayed before scrolling, that is, an “old” information, a user in many cases may desire not to process that old information over again. A user will try to locate the place where old information ends and new information begins to focus on new information. Existing systems provide little support for solving that task. In many applications a fixed number of overlapping lines is typically displayed. Therefore, the user may habitually skip, for example, the first line and focus directly on the second line using its spatial location as a clue. The usefulness of this strategy, however, is limited because the number of overlapping lines may vary between applications. Besides, when a window is scrolled to the last portion of a document new contents can begin anywhere on the page. Therefore, the only effective strategy for locating new information on a page is reading or browsing through all information from the beginning of a page (for instance, in case of scrolling down, from the top of a page) until new information is located. The user has to use the meaning of information to differentiate new information from old information. This strategy is more effort and time consuming comparing to relying on visual clues for locating new information.
None of the above techniques provides effective visual clues for cases when the user scrolls quickly through the content.